1. Field of the Invention
The present invention relates to an image forming apparatus such as an electrophotographic copying machine and a laser printer, and to an image forming method.
2. Description of the Related Art
Image forming apparatuses such as electrophotographic copying machines and printers form images in a following manner.
Charging means charges a photoreceptor such as a photosensitive drum to have a uniform potential at a surface thereof, an image exposure corresponding to an image to be copied or printed is applied to the photoreceptor, and then the electrostatic latent image formed on the photoreceptor is developed by a developing device into a visible image, which is transferred to a recording medium and is fixed thereto.
In this processing, developer on the photoreceptor is not fully transferred to the recording medium, and a transfer efficiency is usually about 80-90%, which means that about 10-20% of the developer is not transferred and remains thereon. This residual developer is generally removed by a cleaning device.
There have been cleaning devices of several types such as web sliding type, fur brush type, roller type and blade type.
However, the prior art cleaning devices have following disadvantages.
(1) If the apparatus is designed to discard the removed developer, there is a great loss of the developer, and if it is designed to reuse the developer, means such a recycle tube for returning it to the developing device is additionally required.
(2) In either case that the developer is discarded or returned to the developing device, a container for temporarily collecting the removed developer and a space for mounting it are required, which increases sizes of the image forming apparatus.
(3) In order to avoid increase of the sizes of the image forming apparatus or the cleaning device of a discard type, if used, in the image forming apparatus, the sizes of the collecting container may be reduced. However, the small container may cause overflow of the developer, particularly when images consuming a small amount of developer are formed, i.e., when black or colored areas of the visible images formed by the developer are small, and thus a quantity of residual developer is large.